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Why SDN and MPLS?
Saurav Das, Ali Reza Sharafat,Guru Parulkar, Nick McKeown
Clean Slate CTO Summit9th November, 2011
2
Why do Service Providers use MPLS?
Really about 2 services
MPLS Services
MPLS VPNs MPLS - TE
Motivation
Highly profitable
No easy way
Older ways not used
Motivation
Deterministic Behavior
Efficient Resource Utilization
Older ways not used
What is Traffic Engineering?
Steering traffic to where the bandwidth is…• good for the traffic - less congestion• good for the network - better resource
utilization
MPLS Solution: • Create tunnels routed over under-utilized
parts of the network • Route traffic through the tunnels
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Video of a Demonstrationshowing MPLS-TE service with SDN/OF
www.openflow.org/videos
OSPF-TE
RSVP-TE
LDP I-BGP
LMP MP-BGP
Label Switched Path (LSP)
PUSH SWAP POP
5
P
OSPF-TE
RSVP-TE
LDP I-BGPOpenFlow
NETWORK OPERATING SYSTEM
Routing Discovery Label Distribution Recovery
TE
LMP MP-BGP
PUSH
Simpler Data Plane
Simpler Control Plane
Services
Network Applications
SWAP POP
Label Switched Path (LSP)
Provide the Services without the Complexity!
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State Distribution Mechanisms
Switch Operating
System
DistributedNetwork Functions
IGP- Route Advert, Link-State
OSPFv2
TE Label Distribution
RSVP-TE
VPN-IPv4 Route Advert
MP-BGP
E-BGP learned Route Advert
I-BGP + RR
PE Label Distribution
LDP
Distributed Network Functions each with their own
State Distribution Mechanisms
Motivation
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1. MPLS doesn’t come cheap• MPLS additional feature on
complex core-routers• Need to support many
protocols
2. MPLS doesn’t come simple• IP/MPLS Control plane
exceedingly complex
OSPFv2
RSVP-TE
MP-BGP
I-BGP + RR
LDP RSVP-TE
MP-BGP
I-BGP + RR
LDPOSPFv2
RSVP-TE
MP-BGP
I-BGP + RR
LDP
Juniper Cisco Brocade
TE TE TE
Auto-RouteAuto-Bandwidth
PrioritiesLoad-Share
DS-TEFRR
Re-opt
Auto-RouteAuto-Bandwidth
PrioritiesLoad-Share
DS-TEFRR
Re-opt
Auto-RouteAuto-Bandwidth
PrioritiesLoad-Share
DS-TEFRR
Re-opt
Motivation
3. Slow pace of Innovation8
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Providing MPLS Services with SDN/OF
OpenFlow
NETWORK OPERATING SYSTEM
Routing Discovery Label Distribution Recovery
TE 2.0
Simpler Cheaper
Multi-VendorData Plane
(1)
Simpler Control Plane
(2)
Services / Network Applications
(3)
SWAP POPPUSH
Application/Service Viewpoint
3 Examples of SDN Benefits:
1. Programmability & Simplicity
2. Extensibility
3. Global -Optimization
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R3
R6
R2R4
R5
R1
Re-routing Packets into Tunnels
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Exposing tunnels to OSPF or IS-IS• N2 problem• Strictly avoided
IP routing (SPF)
TE-LSP routing (CSPF)
PBR/FBF, AutoRoute
Link-state: cost, up/downTE-Link-state: weight, attributes, reservations
Link-state: cost, up/down
R3
R6
R2R4
R5
R1
Re-routing Packets into Tunnels
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Tunnels not Represented here
AutoRoute
Destination Router Next-Hop Total-Cost
R4 R4, OutIntf 12 10
R6 R6, OutIntf 9 10
R2 R4, OutIntf 12 20
R2 R6, OutIntf 9 20
Destination Router Next-Hop Total-Cost
R4 R4, OutIntf 12 10
R6 R6, OutIntf 9 10
R2 TunnIntf T1 20
R3
R6
R2R4
R5
R1
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Routing Table in R5
AutoRoute
IP dest-prefix
via dest-router(in domain)
next-hopnext-hop is tunnel
Automated but Inflexible
Policy Based Routing
IP dest-prefix
via dest-router(in domain)
next-hopHeader-field-matchnext-hop is tunnelor something else
Flexible butNot Automated 14
SDN based Routing
IP routing (SPF)
TE-LSP routing (CSPF)
Static-routes, PBR/FBF, Autoroute
Link-state: cost, up/downTE-Link-state: weight, attributes, reservations
Link-state: cost, up/down
Programmability =>Flexibility + Automation
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Default SPF
Routing
IP network
TE-LSP Routing(CSPF)
VoIP traffic
Routing
Customer traffic
Routing
Load Sharing
Tunnels Represented
here
NOX core(Connection Handler, Event engine)
Switch-API
GUI API
(LAVI)
GUI(ENVI)
OpenFlow protocol
To switches..
Link Discovery
IP Topology
TE-LSP Routing (CSPF)
TE-LSP Configuration Bw. Res. & Priorities
Label DBTE tunnel DB
Packet-flow DB
Controller
TE Applications
Map Abstraction
Network API
TE-LSP Statistics & Auto-Bandwidth
Network API
Default SPF Routing Load SharingTraffic-type Aware Routing
Packet-flow Routing Applications
Controller Internals
~4000 Lines-of-Code
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Application/Service Viewpoint
3 Examples of SDN benefits:
1. Programmability & Simplicity
2. Extensibility
3. Global -Optimization
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L3-VPN
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• 2 new protocols – LDP and MP-BGP
• Implementation in each router
• More code to tie VPN service to protocols
• … and protocols to other protocols
• CLI changes + configuration
• … and eventually standardization
What would it take in today’s networks?
19
NOX core(Connection Handler, Event engine)
Switch-API
GUI API
(LAVI)
GUI(ENVI)
OpenFlow protocol
To switches..
Link Discovery
IP Topology
TE-LSP Routing (CSPF)
TE-LSP Configuration Bw. Res. & Priorities
Label DBTE tunnel DB
Packet-flow DB
Controller
TE Applications
Map Abstraction
Network API
TE-LSP Statistics & Auto-Bandwidth
Network API
Default SPF Routing VPN RoutingTraffic-type Aware Routing
Packet-flow Routing Applications
What did it take with SDN?
Just this!!
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Providing MPLS Services with SDN/OF
OpenFlow
NETWORK OPERATING SYSTEM
Routing Discovery Label Distribution Recovery
TE 2.0 VPNs 2.0
Simpler Data Plane
(1)
Simpler Control Plane
(2)
Services / Network Applications
(3)
Optimized FRR/ AutoBw
MPLS-TP Control
Multi-layer Control
SWAP POPPUSH
Application/Service Viewpoint
3 Examples of SDN Benefits:
1. Programmability & Simplicity
2. Extensibility
3. Global -Optimization
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Auto-Bandwidth/ Re-Opt Timers
23
Churn
Source: NANOG 24
R3
R6
R2R4
R5
Local View Local Optimization
25
Global View Global Optimization
OpenFlow
NETWORK OPERATING SYSTEM
Routing Discovery Label Distribution Recovery
TE 2.0 VPNs 2.0
2. Dynamically Update
Forwarding State
1. Periodic, Online
Global-Opt
Optimized FRR/ AutoBw
MPLS-TP Control
Multi-layer Control
SWAP POPPUSH
Why SDN and MPLS?
Simpler Control – Eliminate protocols, decouple network-functions from state-distribution mechanisms
Simpler, Cheaper MPLS data-plane with SDN control-architecture
Service Innovation – Programmability, Extensibility & Global-Optimization.
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Open vSwitchwith standard
MPLS data plane
Prototype System
Network Operating System (NOX)GUI (Envi)
showing real-timenetwork state
Open vSwitch(with MPLS)Open vSwitch(with MPLS)Open vSwitch(with MPLS)Open vSwitch(with MPLS)Open vSwitch(with MPLS)Open vSwitch(with MPLS)Open vSwitch(with MPLS)Open vSwitch(with MPLS)Open vSwitch(with MPLS)
Open vSwitchwith standard
MPLS data plane
OpenFlow
MPLS GUI MPLS API MPLS StatsCSPF Routing
MPLS-TEAuto – route; Auto – bandwidthTraffic – aware LSPs; PrioritiesTE-LSP configuration
Mininet Environment 28
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